The present invention relates to a post-accident cooling device for the confinement enclosure of a pressurized water nuclear reactor.
Nuclear reactors cooled with pressurized light water for generating electricity are located in confinement enclosures designed for obviating the effects of potential accidents involving the fracture of the wall containing the pressurized water. These enclosures can resist the temperature and pressure conditions due to the rapid expansion of the hot water resulting from such a pressure. However, it is then necessary to cool the reactor core and the actual enclosure to prevent a progressive rise of the pressure and temperature due to the production of residual radioactive power in the core.
Various means have already been proposed for cooling the enclosure under accident conditions. Thus, it is possible to internally sprinkle water by using pumps to deliver water taken from an external reservoir. It is also possible to have within the enclosure a reserve of ice, which is able to cool the enclosure for a significant time without it being necessary to have recourse to an external energy supply.
However, in general terms the hitherto known devices for cooling the enclosure of a reactor require an external energy supply over a varying length of time if it is desired to prevent pressure and temperature conditions which are dangerous for the enclosure. The availability of this energy involves the provision of special installations and leads to a reliability problem in such a way that it is obviously desirable to have a device able to operate in an autonomous manner without any external energy supply.